1. Field of Invention
The present invention generally relates to a process for fabricating an integrated micro spherical lens for an optical switch, and more particularly to a fabrication process utilizing photo etching and electromechanical working process to form an integrated micro spherical lens on the base of an optical fiber array, so as to construct an optical fiber collimator or optical switch.
2. Related Art
Optical communication utilizes optical fibers as transmission media. This started with a low-loss single-mode optical fiber made by Coming Glass of America in 1970. Accompanied by the development of laser diodes, optical communication has been well commercialized.
Optical communication is capable of transferring a lot of information, such as thousands of people""s voices, compressed in individual time frames. Such high capacity cannot be achieved by traditional cooper wire. Moreover, optical fibers are small in size, light weight, high speed, free of noise and distortion, free from electromagnetic interference, wide-banded, and low loss, so as to fulfil the requirements of long distance and high capacity digital communication.
The optical fiber collimator or optical switch is a key component of optical fiber communication. It allows communication signals to fully transmit between fibers without any loss. Therefore, it is the main focus of development for the optical communication industry.
When a laser beam comes out of an optical fiber, the sectional diameter of the beam becomes larger as the distance of its path increases. If the diameter of the beam exceeds the module field diameter (MFD) of the succeeding optical fiber, optical loss will occur. Minor loss will weaken the signal, while major loss will cause communication to fail.
In order to prevent optical loss in the coupling device, a spherical lens has been applied to convert light emitted from a light emitting device, or the emergent end of an optical fiber into a parallel beam of light, or the reverse, to focus a parallel beam of light on a light detecting device or the incident end of an optical fiber. Such an optical part is referred to as a fiber collimator. Fiber collimators are frequently used, for example, in an optical switch for changing over a light path. Optical switches are widely used as basic optical devices, and optical devices that are reliable and suitable for miniaturization are in great demand. The miniaturized spherical lens is developed so as to be light-weight, small in size and cheap, while remaining functional. Currently, a small spherical lens or cylindrical lens with a diameter around 200 to 300 microns can be made. The spherical lens is only half of the diameter of a human hair, so it is difficult for an automatic device to handle it. Therefore, it can only be processed manually. The operator has to precisely position the lens in alignment with the light path, and glue and fasten it when a good coupling signal is obtained. When aligning a lens array, two or more alignment points have to be taken care of, and when one point has been positioned, it can easily lose its position when another point is being adjusted. Thus, repeated operations are needed for assembling the spherical lens in the optical switch, and high cost is inevitable.
Though a conventional spherical lens can be placed in the light path of an optical switch for improving optical coupling, the cost of the lens is high, the operation requires manual handling, and the quality and production rate cannot be improved. Thus, it cannot satisfy the requirements of the increasing market.
Accordingly, it is an object of the present invention to provide a method for fabricating a micro spherical lens for an optical switch, which overcomes such drawbacks of the prior art, as described above.
It is another object of the present invention to provide a method for fabricating an integrated micro spherical lens for an optical switch, which can be mass-produced. It utilizes photo etching and electromechanical working process to form an integrated micro spherical lens on the base of an optical fiber array, so as to construct an optical fiber collimator or optical switch in a low cost and high precision manner.
It is yet another object of the present invention to provide an optical switch having at least an integrated micro spherical lens made from semiconductor fabrication processes.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.